<?php
 date_default_timezone_get();
 date_default_timezone_set('Asia/Kolkata');
//echo date('Y-m-d H:i:s a l',3600*24*365*44);

//echo time();
// get time after one hour
//echo date('h/i/s A l y v= == * ',time()-(60*60*3));

$time = strtotime('-100 days');
echo date('Y-M-d',$time);


